Halloween still scares me to this day - Carpenter just did a masterful job with the music and keeping things simple. The Exorcist is scary - just leaves you with a creepy feeling in your stomach I cant explain. Texas Chainsaw Massacre - very raw movie, creepy, disturbing. Psycho - The masterpiece of all horror films. Nothing even comes close. Rosemary's Baby was more disturbing than scary, but still a good flick.
